Abstract:

A method for operating a dishwasher is provided. The method includes
heating a first amount of liquid in a first partial program step; at
least partially storing the heated first amount of liquid in the interior
of a liquid reservoir, wherein the heated first amount of liquid is in
heat-conducting contact with the interior of a tub; circulating a second
amount of liquid in a second partial program step; and emptying the
liquid reservoir when the second partial program step has been completed.

Claims:

1-11. (canceled)

12. A method for operation of a dishwasher, the method comprising:
heating a first amount of liquid in a first partial program step; at
least partially storing the heated first amount of liquid in the interior
of a liquid reservoir, wherein the heated first amount of liquid is in
heat-conducting contact with the interior of a tub; circulating a second
amount of liquid in a second partial program step; and emptying the
liquid reservoir when the second partial program step has been completed.

13. The method of claim 12, wherein the dishwasher is a household
dishwasher.

14. The method of claim 12, wherein the circulated second amount of
liquid is heated at least at times in the second partial program step.

15. The method of claim 12, wherein the circulated second amount of
liquid is heated only to a temperature that is one of equal to and below
a temperature of the first amount of liquid stored in the liquid
reservoir.

16. The method of claim 12, wherein the liquid reservoir and the tub are
emptied simultaneously.

17. The method of claim 12, wherein first the tub is emptied and then the
liquid reservoir is emptied.

18. The method of claim 12, wherein the first partial program step is a
cleaning step and the second partial program step is a rinsing step.

19. The method of claim 12, wherein a third partial program step is
provided between the first and second partial program steps without
heating at least one of the first and second amount of liquid.

20. The method of claim 19, wherein the third partial program step is an
intermediate rinse step.

21. The method of claim 12, wherein the first amount of liquid stored in
the liquid reservoir is used before at least one of the first and second
partial program step.

22. The method of claim 21, wherein the first partial program step is a
pre-rinse step without heating the first amount of liquid.

23. A dishwasher, comprising: a liquid reservoir; a tub; a heater to heat
a first amount of liquid in a first partial program step; a storage to at
least partially store the heated first amount of liquid in the interior
of the liquid reservoir, wherein the heated first amount of liquid is in
heat-conducting contact with the interior of the tub; a circulator to
circulate a second amount of liquid in a second partial program step; and
an emptying device to empty the liquid reservoir when the second partial
program step has been completed.

Description:

[0001] The invention relates to a method for operating a water-conducting
domestic appliance.

[0002] From DE 27 30 489 a household dishwasher is known, in which for the
cleaning of items to be washed a washing program having a multiplicity of
program steps is performed, which has at least two partial program steps,
during which washing liquor, for example water mixed with detergent or
rinse aid, is heated, where the dishwasher has at least one tub for
accommodating items to be washed and a liquid reservoir in
heat-conducting contact with the tub. It here permits the liquid
reservoir in thermal contact with the tub to heat water, for example
prior to its use in a washing step. This can take place by means of a
temperature difference relative to the environment of the dishwasher
and/or through the waste heat of the washing liquor circulated in the
treatment compartment. An energy saving can thereby be achieved.

[0003] The object of the invention is to specify a method with which the
energy consumption can be further reduced.

[0004] The inventive method for operation of a dishwasher, in particular a
household dishwasher, has at least the following steps: [0005] a first
amount of liquid is heated in a partial program step, [0006] the heated
first amount of liquid is stored, at least partially in heat-conducting
contact with the interior of a tub, in the interior of a liquid
reservoir, [0007] in a further partial program step a second amount of
liquid is heated, and [0008] emptying of the liquid reservoir, when the
further partial program step has been completed.

[0009] The inventive method thus allows regaining of the use of heat
energy of liquids, in particular of heated liquids, which is otherwise
lost upon being pumped out into a domestic wastewater disposal system.

[0010] In a preferred embodiment it is provided for the circulated amount
of liquid to be heated at least for a time in the further partial program
step, so that temperatures can also be achieved which could not be
attained only through the use of recovered heat energy. It can however
also be provided for heating to be dispensed with in the further partial
program step, and instead to use recovered heat energy to heat liquid.

[0011] It is here preferably provided for the circulated amount of liquid
only to be heated to a temperature equal to or below the temperature of
the liquid stored in the liquid reservoir, so that no unnecessary energy
need be applied to heat the liquid stored in the liquid reservoir.

[0012] In a first, preferred embodiment, it is provided for the liquid
reservoir and the tub to be emptied simultaneously, while in a second,
alternative embodiment, it is provided for the tub to be emptied first,
followed then by the liquid reservoir.

[0013] The partial program steps preferably comprise at least one cleaning
step and one rinsing step, where during both partial program steps
liquids are heated in each case. During the cleaning step, detergent is
here added and the circulated liquid or washing liquor heated to, for
example, up to 65° C. In the rinsing step on the other hand,
wetting agents are added, which are in particular intended to ensure a
smear-free drying process for the items to be washed, where temperatures
of for example 70° C. are reached in this step.

[0014] At least one third partial program step without the heating of
liquid can further preferably be provided for between the two partial
program steps. This can here preferably take the form of an intermediate
rinse step, which serves to remove residues of liquid or washing liquor
mixed with detergent remaining in the tub and the pump system of the
dishwasher, in order to ensure that detergent residues and wetting agent
added in the rinsing step do not have mutually negative effects.

[0015] Finally it can preferably be provided for, that prior to a partial
program step, during which liquid is heated, one or more pre-rinse steps
without heating of liquid are provided, in which liquid stored in the
liquid reservoir is used. The pre-rinse serves to remove heavy soiling
from items to be washed.

[0016] The invention further includes a dishwasher, which is embodied for
execution of the inventive method.

[0017] The invention is explained below on the basis of a drawing.

Wherein:

[0018]FIG. 1 shows a schematic representation of a dishwasher for
execution of the inventive method:

[0019] The dishwasher 2 has a tub 6 to accommodate items to be washed (not
shown), which for example can be placed in extendably mounted crockery
baskets (not shown). In order for the items to be washed to have liquid
or washing liquor, that is water mixed with detergent or rinse aid,
applied to them, a spray arm 8 is provided in the tub in the present
exemplary embodiment. A multiplicity of spray arms can however be
provided. A circulation pump 10 is provided to supply the spray arms 8
with washing liquor, which is connected in a liquid-conducting manner
with a sump arranged in the base area of the tub 6, in which the washing
liquor dripping off the items to be washed is collected. A motor 12 is
provided to drive the circulation pump 10, which is connected to a
control device 14 of the dishwasher 2. A heating element (not shown) can
be provided to heat the circulated washing liquor.

[0020] A liquid reservoir 4 in heat-conducting contact with the tub 6 is
provided, in which an amount of liquid can be temporarily stored. A
drainage line 24 is provided in the tub 6 for emptying the liquid
reservoir 4, which can be opened and closed by means of a drain valve 18,
where the drain valve 18 is connected with the control device 14 via a
control line 16.

[0021] Finally a return line 26 is provided, with which it is possible to
convey washing liquor from the tub 6 back into the liquid reservoir 4. A
return valve 20 is provided for the opening and closing of the return
line 26, which is likewise connected to the control device 14 via a
control line 18. Further valves can in addition be provided, to block an
inlet line to the spray arm 8 in the tub 6, if washing liquor is to be
conducted into the liquid reservoir 4 through the return line 26 by means
of the circulation pump 10. A multi-way valve embodied as a water
distributor can further be used instead of individual valves, which for
example has a disk adjustable by means of a motor.

[0022] For the cleaning of items to be washed a washing program comprising
a multiplicity of program steps is run, which can for example encompass
the program steps pre-rinse, washing, intermediate rinse step and final
rinsing, plus drying. The water or washing liquor, that is water mixed
with detergent or rinse aid, is here heated during at least two of these
program steps, for example during the washing and the rinsing step. A
change of washing liquor involving the circulated washing liquor takes
place between the partial program steps, that is after the conclusion of
a partial program step the dishwasher is once more filled with liquid or
water respectively.

[0023] A pre-rinse step can for example be performed, after an amount of
liquid has flowed into the tub 6 via conduit means (not shown). The
amount of liquid is circulated from the circulation pump 10 after
corresponding actuation of the motor 12 by means of the control device
14, and fed to the spray arm 8.

[0024] After completion of the pre-rinse cycle, the amount of liquid is
directed through the return line 26 into the liquid reservoir 4 after
opening of the return valve 20, where a closed drain valve 18 prevents
the tub 4 being emptied once again.

[0025] Finally, for the cleaning step the tub 6 is filled with an amount
of liquid via conduit means (not shown), and the amount of liquid
circulated by means of the circulation pump 10 and simultaneously heated.

[0026] After conclusion of the cleaning step the amount of liquid can be
conveyed from the tub 6 into the liquid reservoir 4 through opening of
return line 26 by means of actuation of the return valve 20.

[0027] In an intermediate rinse step the tub 6 is once more filled with an
amount of liquid and the liquid then circulated with the circulation
pump, without being heated. A heating takes place solely through the heat
transition from the liquid reservoir 4 into the interior of the tub 6, as
the liquid stored in the liquid reservoir 6 has a higher temperature than
prevails in the interior of the tub 6. After completion of the
intermediate rinse step, both the tub 6 and the liquid reservoir 4 are
emptied. This can take place consecutively, starting with the tub 6, or
simultaneously.

[0028] Subsequently in a last step the tub 6 is once more filled with an
amount of liquid for execution of a rinsing step, and the liquid then
circulated with the circulation pump, while being further heated.

[0029] After conclusion of the rinsing step, the tub 6 can be emptied by
means of a conduit means, which is not shown, which allows liquid to be
directed into a domestic wastewater disposal system.

[0030] Provision can also be made, while the amount of liquid present in
the tub 6, that is water mixed with wetting agent or rinse aid, is then
routed into the empty liquid reservoir 4 through the return line 26.

[0031] In the case of a renewed program start, the amount of liquid
temporarily stored in the liquid reservoir 4 is directed into the tub 6
by opening of the drain valve, and used to perform a pre-rinse step.

[0032] Notwithstanding the described program sequence, an energy saving
can also be achieved with the inventive method in the case of
modifications to the program sequence, in which during the intermediate
rinse and/or pre-rinse step a heating of the liquid or washing liquor is
also provided for, or in which the intermediate rinse and or pre-rinse
step are blanked out.